In linguistics we call this “social gender”, which is basically whether a word has a feminine or masculine connotation. This kind of thing can be hard to intuit, since there are no hard and fast rules. Obvious examples include words like “nurse”, which may be technically gender neutral, but it’s got such a strong feminine connotation that many people will clarify “male nurse”. Less obvious examples are words like “muscles”, which all humans have, but the default interpretation is like, a manly guy with bulging biceps.

Many many words have social gender that’s difficult to notice, either because of the natural struggle to see gender, or because it’s just that subtle. So a corpus analysis like this is exciting because it gives concrete data on words we might not have thought twice about!!